Molecular biologist Kaye Lang's theory--that ancient diseases encoded in the DNA of humans can return to life--has become a chilling reality. The shocking evidence: a virus-hunter has tracked down a flu-like disease that kills expectant mothers and their offspring.

A retrovirus is discovered which provokes miscarriages in women, followed by a second pregnancy without sexual intercourse. As scientists race to unlock its mysteries, fears grow it may herald the end of the human race as we know it.